Ignore unknown code move events if --ignore-unknown is set.

I don't like seeing a whole bunch of this in the output

```
...
Code move event for unknown code: 0xe4edbaf8ca0
Code move event for unknown code: 0xe4edbaf8d40
Code move event for unknown code: 0xe4edbaf8e00
Code move event for unknown code: 0xe4edbaf8ee0
Code move event for unknown code: 0xe4edbaf8fc0
Code move event for unknown code: 0xe4edbaf90a0
Code move event for unknown code: 0xe4edbaf9180
Code move event for unknown code: 0xe4edbaf9220
Code move event for unknown code: 0xe4edbaf92c0
Code move event for unknown code: 0xe4edbaf9380
Code move event for unknown code: 0xe4edbafa080
Code move event for unknown code: 0xe4edbafa140
Code move event for unknown code: 0xe4edbafa1e0
Code move event for unknown code: 0xe4edbafa280
Code move event for unknown code: 0xe4edbafa320
Code move event for unknown code: 0xe4edbafa3c0
Code move event for unknown code: 0xe4edbafa4c0
Code move event for unknown code: 0xe4edbafa580
Code move event for unknown code: 0xe4edbafa620
Code move event for unknown code: 0xe4edbafa720
Code move event for unknown code: 0xe4edbafa7c0
Code move event for unknown code: 0xe4edbafa920
...
```

And it seems like the `--ignore-unknown` flag should get rid of it, but currently it does not. This PR would fix that.

Granted, it would be great if node-tick understood the unknown codes, but it still works alright without them.